AU603422B2 - Polypropylene molding material - Google Patents

Abstract

A polypropylene moulding composition essentially comprising a high-molecular-weight homopolymer or copolymer of propylene and from 0.001 to 0.5 % by weight of a nucleating agent from the group comprising sodium benzoate, sodium montanate, calcium montanate, aluminium p-tert-butylbenzoate, quinacridone, naphthalimide, dibenzylidenesorbitol and ultrafine talc gives mouldings of improved hardness and toughness.

Description

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Form 10 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE

SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: or B Published: Priority: Related Art; ,i c This do uraenit contains the awendtnetkis m7ade under Section 49 and is correct for prioting.

iKB~tJtA-r ta "T A S-I fa it fJi Name of Applicant: HOECHST AKTIENGESELLSCHAFT Address of Applicant: Actual Inventor:

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Address for Service 45 Bruningstrasse, D-6230 Frankfurt/Main 80, Republic of Germany JURGEN HELBERG, GERT HEUFER, FRIEDRICH KLOSS WOLFGANG LOW EDWD, WATERS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Federal and Complete Specification for the invention entitled: POLYPROPYLENE MOLDING MATERIAL The following statement is a full dascription of this Invention, including the best method of performing it known to 1.

HOECHST AKTIENGESELLSCHAFT HOE 87/F 043 Dr.Da/je Description Polypropylene molding material The invention relates to a polypropylene molding mater- 11 ial having improved processing characteristics and improved properties.

In the processing of polypropylene, the processing speed and the properties prove inadequate in many cases. There has therefore been no lack of attempts to overcome these deficiencies.

It is known that partially crystalline thermoplastics, i such as polypropylene, can be advantageously affected in S- terms of processing ,haracteristics and properties in i many cases by adding suitable crystallization seeds, socalled nucleating agents. Nucleation leads to a finely spherulitic structure and a higher crystallization temperature Cr The consequence of this is that the product to be prepared is dimensionally stable at a higher temperature and can therefore be removed from the mold at an earlier stage. This results ini a substantial reduction in the I cycle time during injection molding, in particular in the case of thick-walled parts, and in an increase in the take-off speed during extrusion.

The finely spherulitic structure leads to higher transparency and, because of the higher crystallization temperature, to increased crystallinity. At the same time there is an improvement in the hardness and rigidity of the moldings produced therefrom, but a reduction in the toughness properties. This undesired effect has considerably restricted the use of nucleating agents in many cases.

2 It is known that by adding -quinacridone to a high molecular weight propylene homopolymer (cf. German Auslegeschrift 1,188,279) the hardness and toughness of the moldings produced therefrom is increased. and 8quinacridones have only a slight effect; they increase only the hardness without producing any increase at all in the toughness.

Furthermore, the use of aluminum p-tert-butylbenzoate and dibenzylidenesorbitol as nucleating agents for propylene copolymer is known (cf. EP-A-137,482). However, talc is added to increase or maintain the low-temperature toughness. An improvement in the transparency and satisfactory rigidity and low-temperature toughness are achieved. Improvement of the hardness is not mentioned.

o 15 EP-A-137,482 suggests that the desired effects of talc Ce c addition cannot be obtained if the amount added is less than c 0.01 parts by weight. Similarly, if the quantity added is I in excess of 3.0 parts by weight, the transparency of the copolymer composition is poor.

It was the object to find a propylene polymer for aJ moldings having improved toughness nd hardness.

It has been found that the object can be achieved by a propylene polymer which contains certain nucleating agents.

The invention therefore relates to a polypropylene Ss omolding material essentially consisting of a homopolymer or a copolymer of propylene with ethylene or butene, having a melt flow index MFI 230/5 of less than or equal to 5 min and containing 0.001 to 0.5% by weight, based on the I ig30 molding material, of one nucleating agent from the group consisting of sodium benzoate, sodium montanate, calcium S montanate, aluminium p-tert-butylbenzoate, quinacridone, naphthalimide, dibenzylidenesorbitol and ultrafine talc.

The effectiveness of talc as a nucleating agent is 35 especially surprising in the light of the prior art.

I SIRA ooloh H I 0 to I i n otann%.0Vo .%bTegtbsdo h -2a- Suitable homopolymer and copolymers for the molding material according-to the invention are homopolymers and 4 have a high molecular weight. Their roelt flow index MFI 2305 isless than or equal to 5 g/10 min (MFI 0 0015 0 0 0 00 0 0 00 00 0 0 00 10000.

00 0 0 2 0 030 1 I 3 230/2.16 about 1 g/10 min), preferably less than or equal to 2 g/10 min (MFI 230/2.16 about 0.5 g/10 min).

The nucleating agents used are sodium benzoate, sodium montanate, calcium montanate, aluminum p-tert-butylbenzoate, quinacridone, napthalimide, dibenzylidenesorbitoL and ultrafine tatc. Sodium benzoate, quinacridone and ultrafine talc are preferred, in particular sodium benzoate. The particle size of these nucleating agents is Less thsn or equal to 20 pm, preferably less than or equal to 10 pm. The substances are added to the polymer in an amount of 0.001 to 0.5% by weight, preferably 0.001 to 0.15% by weight.

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0 0 C9GC P C I CC CO C I SI C CO. S C IC The molding material according to the invention can contain the conventional additives which facilitate processing and improve the physical and chemical properties.

Examples of these are Light stabilizers and heat stabilizers, antioxidants, antistatic agents, lubricants, antiblocking agents and fillers and reinforcing agents, colored pigments, synthetic and natural resins, rubber- Like products and flameproofing agents. The first group is present in the molding material in general in an amount of 0.01 to 5% by weight, based on the amount of polymer filler). Fillers and reinforcing agents, colored pigments, synthetic and natural resins, rubber-like products and flameproofing agents are used in an amount corresponding to the particular requirements.

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a The nucleating agents are incorporated into the propylene polymer in a known manner, for example by means of a mixer, extruder, roll or kneader or by air homogenization, it being also possible to use a masterbatch of the nucleating agents for incorporation.

The molding material according to the invention not only results in improved toughness and improved hardness of the moldings in comparison with moldings obtained from -n; 1 4 an identical molding material without the stated nucleating agents, but also possesses better processing characteristics. Thus, it permits shorter cycle times during injection molding and higher take-off speeds during extrusion of pipes and sections. Moreover, sticking of the plastic material to the mold is reduced during blow molding as a result of the formation of skin of higher crysta-l-inity on the surface of the parison.

The molding material according to the invention can therefore particularly advantageously be used for produc- Sing thick-walled parts (for example cooling water reservoirs for motor vehicles) by injection molding, panels *a 0 0 0o and pipes by extrusion and hollow articles, contoured o" articles (for example cases) and industrial articles 0000 o 15 (for example bumpers, spoilers, etc.) by blow molding.

0 S oo000oo000 0 0 oo eoo If sodium benzoate is used as the nucleating agent, the presence of calcium stearate as an acid acceptor can be dispensed with. Calcium stearate furthermore has an 0 00 00 adverse effect on nucleation with sodium benzoate.

0o 0 The Examples which follow are intended to illustrate Sthe invention: Examples 1 to 7 and Comparative Examples A to 0 *604 Several high molecular weight (MFI 230/5 5 g/10 min) and low molecular weight (MFI 230/5 5 g/10 min) pulverulent homopolymers of propylene and copolymers of S propylene with ethylene were mixed with various nucleating agents and, either as a powder or as granules, were processed to test specimens. In the same manner, test specimens which did not contain any nucleating agents were prepared for comparison. The hardness and the toughness of the test specimens were measured. The composition of the molding materials tested and the results of the measurements are summarized in Tables 1 and 2.

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S* 4 '4 44 TabLe 1 (Compa rat ive: ExampLes

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B

2

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3

D

4

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Type HomopoLymer to CopoLymer

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is to it is InitiaL PP

APP

CZ by wt.) 4 'Il powdei

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2

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4 (X by 5 7 Startingmixure o (4 (4 :Starting :mixtures r MFI 230/5 wt.) (Cdle0 min) 0.26 0.30 ',T5 0.25 3.2 It i, 9I C Q (4 00 (4 (4 44 0 4 NucLeating agent Type Concentration SX by wt.) Quinacridone 0.001 Quinacridone 0.001 Na benzoate 0.1 AL-o-tert-butvt- 0.05 i benzoate AL-p-tert-butyLbenzoate Ca nontanate ULtrafine taLc AL-p-tert-butyLbenzoate 4 00 0 0 0 00 4 0 00 9900 9 0 0 0 0000 0 0000 00* 9 0 0 4 0 00 00 C~ 0 0 0 0 0 0 o 0 nOn n 0 0 o C, '1 0 ~00 0 TabLe 1 (continued) (Comparative) Examples Hi C

HZ

i H 12

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K2 Li C L2 Ml M2 Type opolymer It omopoLymer If of of o po Lyme r

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off to

APP

by wt.) Initial PP powder

C

2

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4 MFI 230/5 (Z by W1/l min) 9 '18.5 55. 4 35.2 9 21.1 9 21 go to Nucleating agent Type Concentration by wt.) Na benzoate ULtrafine taLc ULtrafine talc tittrafine talc ULtrafine taLce 0 0 09 00 0 0 0 9 0 0 0 9 00 0 9 0 0a 9o 09 0 90 00 0 0 9 o 0 0t 9, 9 99+ 0 0 0 90 0000 9 0 0 .oO 9 06 0 0 r Tab1je 2 FINISMED PRODUCTS cparative MFI 230/5 Form Hiardess/rigidity Exap- BIHI Fa'1 2 Conressive strength akv 3 (WJlrwv) Strength in drop test Drc test/sheets 1 min bottles bottLes 4 H 505 value (PC (PC -200C 0/10 (N/nun 2 3 mun max. 23PC (PC -20C (cm (cm) (cm) A 0.94 Granues 65 16 i 0.93 It 68 25- B 0.83 Granrues 51 12- 2 0.85i 53 21- C 0.25 Ritver 800 110 17 9 3 0.25 a- 1150 165 30 250 N 0.6 Grarules 850 123 15 150 3 0.6 -9 1150 183 23 230 0 5.0 GranuLes 950 128 11 180 3 5.0 1160 210 11 20 D 6.0 Grarutes 56 161 193 10.7 186 4 6.2 It 62 179 213 14.1 167 E 3.7 GranuLes 54 877 34.8 181 14.4 240 130 3.8 11 58 1(59 36.527.8 19.6 250 143 i

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Ii F b~ nr a a *s crn n 4 4 4 44 4404 C 4 4 Sr 440 0Q44 #44g 0 4 4D 0 0 0 940 00 44 0) 4 4 0 0 0 4, 0p 6 0 0 44040 4 45 4 44004 t 004 00) 4) 0 Table 2 (ccrtinued) (bparative MFf 23015 Form BGnp FISHED PRODUCTS itbress/rigidity

BIH

1 FC14P 1 min vatue Conressive strength bottles (N) akv 3 InJ/mrr?) Strength in drop test bottles 4

OOC

Drop test/sheets H 5G9 OOC -2PC q/uG (Nfnwi?) W/nw) 3 m max. 230C (PC -20PC (cm) (cm) (cm) F 3.7 Granutes 54 877 34.8 18.1 14.4 240 13) 6 3.5 to 56 963 36.8 23.3 260 160 G 3.7 Grarules 54 877 34.8 18.1 14.4 240 13) 7 4.0 of 56 1060 373 24.6 130 21.8 244 62 63 165 163 59 160 157 Gra-ules

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Grarub-

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Grarutes of 6ranute: It GrauLes is 1265 1409 1520 1710 1460 1730 1050 1200 980 1070 20.2 15.8 3.9 3.1 12-3 10.8 3.4 2.9 11.2 9.0 7.4 5.2 ~r il- :r ir:2: 9 Notes on Table 2 1) BIH: BaLL indentation hardness, DIN 53,456, 4 mm sheet 2) FCM: FLexural creep modulus, 1 min value, flexural 2 creep test b 5 N/mm 2 3) akv: notched impact strength, corresponding to DIN 53,453, standard smaLL bar with V notch 4) Compressive strength/strength in drop test, bottles: (industrial test, HenkeL) a. Compressive strength A defined hollow article (parting container 700 mL, g) is subjected to a load, and the force in N is oo o measured at 3 mm and maximum deformation.

oS' b. Progressive drop test DaS 15 Test temperature

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o 30 thermostated bottles are filled with water and oaaeoa S° placed on a drop table and allowed to fall onto a concrete floor, the height of fall being increased o" stepwise. The bottles which have remained intact are a 20 tested again with an increased height of fall, until the final bottle has been destroyed.

t The height at which 50% of the bottles are destroyed (h 50 value) is determined.

5) Drop test, sheets ("Lukall", Hoechst) S 25 Test temperatures 23 0 C, 0°C, -20°C, -40 C Falling ram 2 kg 6 sheets are tested in each case at different heights of fall. The end of the test corresponds to the height at which all 6 sheets are destroyed. The mean is calculated from this to give the mean height of fall.

Claims (4)

1. A polypropylene molding material consist- ing of a homopoLymer of propylene or a copoLymer of propylene with ethylene or butene, having a meLt flow index MFI 230/5 of Less than or equal to 5 g/10 min and containing 0.001 to 0.5% by weight, basedon the molding material, ofa nucleating agent from the group consisting of sodium benzoate, sodium montanate, cal- cium montanate, aluminum p-tert-butyLbenzoate, quin- acridone, naphthalimide, dibenzyL idenesorbito~jazt uLtrafine talc;.

2. A molding materiaL as claimed in claim 1, wherein the nucleating agent is sodium benzoate, aluminum p-tert- butyLbenzoate, calcium rontan~te, quinacnidone or ultra- fine talc.

3. A molding material as claimed in claim Z, wherein the nucleating agent is sodium benzoate, quinacridone or ultrafine talc.

4. A process for improving the hardness and toughness of propylene mold ings by adding nucleating agents to the molding material intended for the production of the moldings, wherein 0.001 to 0.5% by weight, based on the moLding material, of a nucleating agent from the consistino of sodium benzoate, sodium montanatO, C4 cium, montanate, aluminum p-tert-butyLbenzootg, quin" acr idone, naphtha(l iide, dibenzyL idemesorbitolk"-ri uLtrafine talc is. added to the molding ratoriaLs*r 44 consisting of a homopoLymer of propylene or a copoLymer of propylene with ethyiere or buteno, having a melt fLow index MFI 930/5 of Less than or equdL to g/10 min. The process as claimed in claim 4, wherein th. nocloating agent is sodium bonzoate, aLuminum p-trt-butbozoae, caLciumn montanatee cuinaenidone or Qltrpflne tae.,- DATED Ulk ts h (10Y Of FCbruIVy 1088, tIONCIISTI AtrnNGEsELLsi AtI HIM). WIEN~S &zRM mINL 6UNL; Vi, ~O 4 #1